My super200P also has a current knob on the pedal. I made graduations on the pedal showing the % of power from 0-100%. Nothing very fancy... I think I just used correction fluid! It's OK, given that the pedal just gets kicked around on the floor. I'm sure one could do a much better job, but it does the trick.

If I recall correctly, there were some graduations on it when it was new, but they did not line up with the range of the knob travel. That made it hard to determine how it was adjusted just by looking at the pedal, so I used solvent to wipe off the old graduations, and "redid them" according to their true adjustment range.
Oh by the way, the knob broke (during original shipment of the welder... which was a few years ago.) so I replaced it with this style that is used on many old school guitar amplifiers. The long pointer of this replacement knob is quite functional however, in that it makes it easier to read where the current is set from the perspective of looking down on it from above.
'13 Everlast 255EXT
'07 Everlast Super200P